In recent years, a fluid analysis model has been generated according to an apparatus model of three-dimensional computer aided design (CAD), in order to conduct a thermal fluid analysis of an electronic/electric apparatus or the like. In thermal fluid analysis using the fluid analysis model, ventilation resistance, air quantity and the like may be predicted from the shape of the apparatus and the performance of the fan according to the fluid analysis. In addition, the temperature of each section of the apparatus may be predicted by thermal analysis by providing the heat-generating conditions for heat-generating elements.
Fluid analysis models are roughly divided into a detailed model in which only a part of the apparatus model is simplified, and a simplified model in which the entire apparatus model is significantly simplified. The simplified model is a fluid analysis model that is more simplified than the detailed model.
The detailed model is generated by changing the corner sections of the apparatus model from curves into square corners, and removing screws and dowels from the apparatus model. The analysis time may be reduced by conducting the fluid analysis using the detailed model, compared with the case in which the apparatus model is used without any change.
The simplified model is generated by replacing each component model included in the apparatus model with a significantly simplified shape such as a cuboid or the like. The analysis time maybe further reduced by conducting the fluid analysis using the simplified model, compared with the case in which the detailed model is used.
When there is an aperture on a surface of a plate-shaped component, the user sets the aperture ratio or the aperture area for the plate-shaped component model included in the simplified model. The aperture ratio of a component model represents the ratio of the area of the aperture of the component model to the surface area of the component model.
The target value of the aperture ratio of each component included in the apparatus is determined in the design stage, and therefore, the designer knows the aperture ratio and is able to set the same aperture ratio for the component model included in the simplified model. Meanwhile, when a person other than the designer conducts a fluid analysis, the aperture ratio for a component model is obtained by calculating the aperture area according to the shape and the number of apertures in the apparatus model or by calculating the aperture area from the shape of the gap between component models.
Recently, environments for conducting the thermal fluid analysis using the detailed model are being established with improvements in the performance of computers and in the performance of the fluid analysis software. However, the detailed model consumes more calculation resources than the simplified model, and therefore, the simplified model is used when the thermal fluid analysis is to be performed in a large number of patterns, when the thermal fluid analysis is to be performed in a short period of time, and when the available calculation resources are limited.
Meanwhile, in an acoustic analysis according to the Statistical Energy Analysis (SEA) method, an SEA model is generated as an acoustic analysis model. The acoustic power transmitted from the sound source such as a fan or the like inside an apparatus to the outside of the apparatus may be predicted by calculating the loss within the SEA elements (internal loss) included in the SEA model and the loss between the SEA elements (coupling loss) according to the acoustic power of the sound source.
The SEA method is an acoustic analysis method based on the existence of at least one mode in the sound field element that is the model of the portion of the space inside the apparatus. The SEA method is suitable for the prediction of high-frequency sounds because, assuming the same cubic volume, the higher the frequency, the more modes exist, and the greater the cubic volume, the more modes exist. Instead of the detailed model, the simplified model is used as the SEA model, because a sound field element that has a large cubic volume to some extent is desirable for the SEA method.
The Finite Element Method (FEM) is known as an acoustic analysis method other than the SEA method. In the FEM, the acoustic analysis may be conducted without changing the detailed model, but the number of modes for high frequency increases, and the mesh becomes finer. For this reason, the FEM is often used for the acoustic analysis for low frequency.
A statistical energy analysis method in which optimal division of subsystems is performed is also known (for example, see Patent document 1). In this statistical energy analysis method, vibration is sequentially applied at a plurality of points in each of arbitrarily divided subsystems, and the vibration speed of the structural object at the time of each application of vibration is sequentially measured at a plurality of points. Then, an addition average value of the respective square vibration speeds is obtained from the respective vibration speeds measured in the respective subsystems, and whether adjacent subsystems are different subsystems or the same subsystems are determined according to whether or not the difference between the addition average values between the adjacent subsystems exceeds a threshold.
An analysis support program that makes it possible to make the work for generating the analysis model efficient is also known (for example, see Patent document 2). According to this analysis support program, a three-dimensional figure that surrounds a target object and a three-dimensional figure that surrounds each component in the group of components included in the target object are generated, according to design information with respect to the target object. Then, among a plurality of elements divided in the three-dimensional figure that surrounds the target object, an element that belongs to the three-dimensional figure that surrounds each component is determined, and a space model that represents the space in which each component exists is generated according to the element that belongs to the three-dimensional figure that surrounds each component.
A data processing program in which the projection range including the group of components to be the projection target may be easily set is also known (for example, see Patent document 3). An SEA method using the coupling loss factor (CLF) between sound field elements is also known (for example, see Non-patent document 1 and Non-patent document 2).
Patent document 1: Japanese Laid-open Patent Publication No. 11-337402
Patent document 2: Japanese Laid-open Patent Publication No. 2012-252522
Patent document 3: Japanese Laid-open Patent Publication No. 2013-120456
Non-patent document 1: SUZUKI et al., “The Simple Software Development for SEA Analysis by Using Matlab”, The 43rd Academic Lectures of the College of Industrial Technology, Nihon University, p. 47-50, 4 Dec. 2010
Non-patent document 2: TAKAHASHI et al., “Comparison between Hybrid SEA Model and Conventional SEA Model for Vehicle Audio Analysis—II. Comparison with Hybrid SEA Model—”, The 43rd Academic Lectures of the College of Industrial Technology, Nihon University, p. 55-58, 4 Dec. 2010